Diet, Lung Function, and Asthma Exacerbations in Puerto Rican Children

Abstract

Changes in dietary patterns may partly explain the epidemic of asthma in industrialized countries. The objective of this study was to examine the relationship between dietary patterns and lung function and asthma exacerbations in Puerto Rican children. This is a case-control study of 678 Puerto Rican children (ages 6-14 years) in San Juan (Puerto Rico). All participants completed a respiratory health questionnaire and a 75-item food frequency questionnaire. Food items were aggregated into 7 groups: fruits, vegetables, grains, protein, dairy, fats, and sweets. Logistic regression was used to evaluate consumption frequency of each group and asthma. Based on the results, a dietary score was created [range from -2 (unhealthy diet: high consumption of dairy and sweets, low consumption of vegetables and grains) to 2 (healthy diet: high consumption of vegetables and grains and low consumption of dairy and sweet)]. Multivariable linear or logistic regression was used to assess the relationship between dietary score and lung function or asthma exacerbations. After adjustment for covariates, a healthier diet (each 1-point increment in dietary score) was associated with significantly higher %predicted forced expiratory volume in the first second (FEV₁) and %predicted forced vital capacity (FVC) in control subjects. Dietary pattern alone was not associated with asthma exacerbations, but children with an unhealthy diet and vitamin D insufficiency (plasma 25(OH)D <30 ng/mL) had higher odds of ≥1 severe asthma exacerbation [odds ratio (OR) = 3.4, 95% confidence interval (CI) = 1.5-7.5] or ≥1 hospitalization due to asthma (OR = 3.9, 95% CI = 1.6-9.8, OR = 3.4, 95% CI = 1.5-7.5) than children who ate a healthy diet and were vitamin D sufficient. A healthy diet, with frequent consumption of vegetables and grains and low consumption of dairy products and sweets, was associated with higher lung function (as measured by FEV₁ and FVC). Vitamin D insufficiency, together with an unhealthy diet, may have detrimental effects on asthma exacerbations in children.

Keywords: asthma; asthma exacerbation; children; diet; lung function.

FIG. 1.

Lung function and dietary score by case–control status. Dietary score ranges from −2 (most “unhealthy diet”) to +2 (most “healthy diet”). Study participants were assigned a score of +1 for high consumption of healthy food groups or −1 for consumption of unhealthy food groups.

FIG. 2.

Multivariate analysis of asthma exacerbation by dietary pattern and vitamin D status. All models were compared with children with healthy diet without vitamin D insufficiency (reference group) and adjusted for age, sex, annual household income, parental history of asthma, BMI z-score, breastfeeding, outdoor physical activity, and early life exposure to second-hand smoke. Dietary pattern: healthy diet (dietary score ≥1) as compared with unhealthy diet (dietary score ≤0). *P < 0.05; **P < 0.01. BMI, body mass index.